A type of endo-prosthesis device, commonly referred to as a stent, is placed or implanted within a blood vessel for treating stenoses, strictures or aneurysms and the like in the blood vessel. These devices are implanted within the vascular system to reinforce collapsing, partially occluded, weakened, or abnormally dilated sections of the blood vessel. Stents also have been successfully implanted in the urinary tract or the bile ducts to reinforce those body vessels.
The present invention generally relates to stents and to the use thereof. Such stents are generally tubular in configuration, are open ended, and are radially expandable between a generally unexpanded insertion diameter and an expanded implantation diameter which is greater than the unexpanded insertion diameter. Such intravascular implants are used for maintaining vascular patency in both humans and animals.
Stents are typically placed or implanted by a mechanical transluminal procedure. One common procedure for implanting a stent is to first open the region of the vessel with a balloon catheter and then place the stent in a position that bridges the weakened portion of the vessel. Prior art patents refer to the construction and design of stents as well as apparatus for positioning stents within a vessel. In general, such patents disclose a technique for positioning an elongated cylindrical stent at selected regions in a vessel. The stent expands to an implanted configuration after insertion with the aid of a catheter.
Specifically, U.S. Pat. No. 4,733,665 to Palmaz which issued Mar. 29, 1988, discloses a number of stent configurations for implantation with the aid of a catheter. The catheter includes means for mounting and retaining the stent, preferably on an inflatable portion of the catheter. The stent is implanted by positioning it within the blood vessel and monitoring its position on a viewing monitor. Once the stent is properly positioned, the catheter is expanded and the stent separated from the catheter body. The catheter can then be withdrawn from the subject, leaving the stent in place within the blood vessel. U.S. Pat. No. 4,950,227 to Savin et al., which issued on Aug. 21, 1990 is similar.
Another similar U.S. Pat. No. 5,019,090 discloses a generally cylindrical stent and a technique for implanting it using a deflated balloon catheter to position the stent within a vessel. Once the stent is properly positioned the balloon is inflated to press the stent against the inner wall linings of the vessel. The balloon is then deflated and withdrawn from the vessel, leaving the stent in place. A patent to Dotter, U.S. Pat. No. 4,503,569 which issued Mar. 12, 1985 discloses a spring stent which expands to an implanted configuration with a change in temperature. The spring stent is implanted in a coiled orientation and heated to cause the spring to expand due to the characteristics of the shape memory alloy from which the stent is made. Similarly, U.S. Pat. No. 4,512,338 to Balko et al., which issued Apr. 23, 1985, discloses a shape memory alloy stent and method for its delivery and use.
Another stent of interest and to which this invention is applicable is described in U.S. patent application Ser. No. 08/246,320, filed May 19, 1994, the entire contents of which is incorporated herein by reference.
All of the above-identified patents are incorporated herein by reference.
It should be understood that the following disclosure is not intended to be exclusive and that any body vessel which has been narrowed, weakened or in any other way requires a reinforcement may be subject to the present invention. Also, as utilized herein, the term vessel is used in a generic sense to include body channels including but not limited to, artery, vein, esophagus, bile duct, urethra, trachea, and the like and that the term body includes not only humans but animals as well. The stent configuration may vary widely from that disclosed.